I went from detesting it to loving it to resenting it to being "meh" about it to waiting 10 years to read the last book to thinking, "Hey, Deathly Hallows is actually much better than the movies!"
Yes, while not my all-time favorite book series, my opinion of them is considerably high. I'd like to reread "The Science of Harry Potter," more closely than I did the first time. I also ought to take another look at Fantastical Beasts and Where to Find Them, which was originally a field guide with annotations by Harry, Ron and Hermoine.
Although I do think its influence on other authors was awful. After it was published, several people thought school dramas were the way to go. R. L. Stine tried to cash-in by writing a gross-out themed school drama series called "Rotten School." Some guy with the pen name Derek the Ghost wrote a horror-themed series called "Scary School." It's like they read Harry Potter, got jealous, then started playing Mad Libs with the content.